Interconnected aluminum and silver members and method of connecting the same or the like



1969 c. R. DIXON 3,471,677

INTERCONNECTED ALUMINUM AND SILVER MEMBERS AND METHOD OF CONNECTING THESAME OR THE LIKE Filed May 26. 1965 IN! 'ENTOR. CHARLES R. DIXON HISATTORNEYS United States Patent 3,471,677 INTERCONNECTED ALUMINUM ANDSILVER MEMBERS AND METHOD OF CONNECTING THE SAME OR THE LH(E Charles R.Dixon, Henrico County, Va., assignor to Reynolds Metals Company,Richmond, Va., a corporation of Delaware Filed May 26, 1965, Ser. No.459,013 Int. Cl. B23k 11/16, 11/20 US. Cl. 219-118 12 Claims ABSTRACT OFTHE DISCLOSURE This disclosure relates to a method of joining analuminum metallic member and a silver member together by disposing afirst portion of a silver member against one side of an aluminum memberso that a second portion of the silver member passes through an openingin the aluminum member and beyond the other side of the aluminum memberto be secured thereto by a subsequent heating of the projecting part toform a eutectic bond between the second portion of the silver member andthe other side of the aluminum member.

This invention relates to an improved product wherein a silver member ismetallurgically interconnected to an aluminum member. This inventionalso relates to an improved method of metallurgically interconnectingtogether such members or the like.

It is well known that it is relatively difficult to metallurgicallysecure a silver member to an aluminum member because when a flux isutilized in the welding process, a corrosion problem exists becausesilver and aluminum in the presence of moisture are disastrouslycorrosive.

However, according to the teachings of this invention, an improvedmethod has been found whereby a silver member can be readily joined toan aluminum member without the use of a flux or the like which wouldpresent a corrosion problem.

It has been found that such a method is particularly adaptable toprovide a Switching arm for an air brake switching device or the like.However, it is to be understood that there are a great number of otheruses of this invention.

For example, it is well known that certain air brake switching deviceswill have a switch arm which might be twelve feet or more or less inlength and when normally formed of copper, the switch arms are too heavyfor proper actuation thereof causing an uneconomical situation.

However, according to the teachings of this invention, the switch armcan be formed of light-weight aluminumcontaining material and can havesilver contacts secured thereto according to the methods of thisinvention where by the silver contacts will provide the means forinterconnecting the switch arm to the switch contact spring blades ofthe electrical switching device.

Accordingly, it is an object of this invention to providemetallurgically interconnected aluminum and silver members.

Another object of this invention is to provide an improved method ofmetallurgically interconnecting such members or the like.

Other objects, uses and advantages of this invention are apparent from areading of this description which proceeds with reference to theaccompanying drawings form ing a part thereof and wherein:

FIGURE 1 is a fragmentary cross-sectional view illustrating one of theinitial steps for forming the improved structure of this invention.

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FIGURE 2 is a view similar to FIGURE 1 and illustrates the silver andaluminum members fully interconnected together according to theteachings of this invention.

FIGURE 3 is a fragmentary perspective view illustrating an electricalswitch arm formed according to the teachings of this invention.

FIGURE 4 is a fragmentary cross-sectional view taken on line 44 ofFIGURE 3.

FIGURE 5 is an end view of the structure illustrated in FIGURE 3 andillustrates the switch arm in another operating position thereof.

While the various features of this invention are hereinafter illustratedand described as providing an improved switch arm for an electricalswitching device or the like, it is to be understood that the variousfeatures of this invention can be utilized singly or in any combinationthereof to provide other structure as desired.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings, because the drawings are merely utilized toillustrate one of the Wide variety of uses of this invention.

As illustrated in FIGURE 1, an aluminum-containing metallic member 10 isprovided and has opposed surfaces 11 and 12. An opening 13 passesthrough the aluminum member 10.

A silver member 14 is provided and has a first portion 15 adapted toabut against the side 12 of the aluminum member 10 While a secondportion 16 thereof passes through the opening 13 in the aluminum member10 and projects beyond the side 11 thereof a suitable distance, theportion 16 being snugly fit in the opening 13 of the aluminum member 10.

Thereafter, the projecting part 17 of the portion 16 of the silvermember 14 is sufficiently heated without flux to cause the same to forma eutectic bond 18 with the aluminum member 10 in the manner illustratedin FIGURE 2 whereby the eutectic bond 18 secures the portion 16 of thesilver member 14 to the side 11 of the aluminum member 10 with theeutectic bond 18 extending into the opening 13 a substantial distancewhereby the silver member 14 is securely fastened to the aluminum member10.

In the embodiment illustrated in FIGURES 1 and 2, the silver member 14comprises a of an inch silver brazier head rivet and the aluminum member10 comprises a 0.235 of an inch thick aluminum alloy 6063 plate. About0.163 of an inch of the portion 16 of the silver member 14 projectsbeyond the side 11 of the aluminum member 10 as represented by thereference numeral B.

A balanced wave tungsten arc welder 19, FIGURE 1, is utilized to supplythe heat and the arc 20 was drawn to the silver rivet 14 until it issutficiently heated to allow the silver to alloy with the aluminum toform the eutectic bond 18.

By using amperes for 40 to 45 seconds, it is possible to consistentlymake metallurgical joints between the silver members 14 and aluminummembers 10 With the balanced wave tungsten arc welder 19.

The arc welder 19 comprises a tungsten heliarc whereby flux was notrequired, the are 20 being argon or argon and helium shielded in aconventional manner.

Thus, it can be seen that this invention provides not only an improvedarticle wherein a pure silver member 14 is interconnected to analuminum-containing metallic member 10, but also this invention providesan improved method of making such an improved article or the like.

For example, the structure and method of this invention as illustratedin FIGURES 1 and 2 can be utilized to make an electrical switchingdevice as generally indicated by the reference numeral 21 in FIGURES 3and 5.

As illustrated in FIGURES 3 and 5, the electrical switching device 21includes a light-weight aluminumcontaining metallic hollow tubularmember 22 suitably mounted for pivotal and rotational movement at theend 23 thereof and carrying pure silver contact members 24 on the end 25thereof, the end 25 of the switch arm 22 being movable between a pair ofspring switch blades 26 in a conventional manner and, thereafter, berotated 90 in the manner illustrated in FIGURE to place the silvercontacts 24 into electrical contact with the spring blades 26 to providethe electrical switching function in a conventional manner.

By forming the hollow tubular metallic member 22 with flat portions 27as illustrated in FIGURES 2-4, the silver contact members 24 can bemetallurgically bonded thereto according to the method of this inventionby having a first portion 28 thereof disposed against the external side29 of the aluminum member 22 and have a second portion 30 thereofprojecting through an opening 31 in the wall of the tubular member 22 soas to project beyond the internal side 32 thereof and be bonded theretoby the eutectic bond 33 formed by the method illustrated in FIGURE 1.

If desired, first portions 15 and 28 of the silver members 14 and 24 cancompletely overlap the aluminum member or 22 around the openings 13 and31 thereof as desired.

Thus, it can be seen that the structure and method of this invention canbe readily utilized to provide an improved switch arm for an electricalswitching device or the like wherein Weight problems are eliminated without sacrifice of efficiency.

However, it is to be understood that the various features of thisinvention can be utilized to provide other articles as desired.

While reference has been previously made to a balanced wave tungsten arcwelder for making the various joints of this invention, it is to beunderstood that an unbalanced wave machine could be utilized to form thejoints of this invention.

In addition, it has been found according to the teachings of thisinvention that silver members of either pure silver or coined silver ofabout 1% inches long can be secured to aluminum members of alloy types6063 and 6061 by the method of this invention with the resulting jointsfunctioning in the manner previously described.

Accordingly, this invention not only provides metallurgicallyinterconnected aluminum and silver members without the use of corrosiveproducing fluxes, but also this invention provides an improved method ofmetallurgically interconnecting such members.

While the form of the invention now preferred has been disclosed asrequired by the statutes, other forms may be used, all coming within thescope of the claims which follow.

What is claimed is:

1. A method of joining an aluminum-containing onepiece, solid andhomogeneous metallic member and a one-piece, solid and homogeneoussilver member comprising the steps of forming an opening through saidaluminum member, disposing a first portion of said silver member againstone side of said aluminum member and a second portion of said silvermember through said opening and beyond the other side of said aluminummember, applying an electric are against the end of said portion of saidsilver member which extends beyond the other side of said aluminum suchthat substantially all the are generated heat flows by conductionthrough said silver member to said aluminum member bringing each memberto their eutectic temperature, thereby forming a eutectic bond betweensaid second portion of said silver member and the other side of saidaluminum member solely from the material of said silver member and saidaluminum member whereby said members are fastened together, and removingsaid are when said eutectic temperature is reached.

2. A method as set forth in claim 1 and including the step of extendingsaid eutectic bond into said opening.

3. A method as set forth in claim 1 and including the step of formingsaid silver member from pure silver.

4,. A method as set forth in claim 1 and including the step of snuglyfitting said second portion of said silver member in said opening.

5. A method as set forth in claim 1 and including the step of completelyoverlapping said one side'of said aluminum member around said openingwith said first portion of said silver member.

6. A method as set forth in claim 1 wherein said are is provided by atungsten heliarc.

7. A method for making an electrical switching device comprising thesteps of providing a hollow tubular aluminum-containing, one-piece,solid and homogeneous metallic switch arm, forming an opening throughone wall of said switch arm, disposing a first portion of a onepiece,solid and homogeneous silver contact member against the external surfaceof said one wall and a second portion of said silver member through saidopening and projecting beyond the internal side of said one Wall,applying an electric are against the end of said portion of said silvermember which projects beyond the internal side of said one wall suchthat substantially all the are generated heat flows by conductionthrough said silver member to said one wall of said aluminum memberbringing each member to their eutectic temperature, thereby forming aeutectic bond between said second portion of said silver member and saidinternal side of said one wall of said switch arm solely from thematerial of said silver member and said arm whereby said arm and contactmember are secured together, and removing said arc when said eutectictemperature is reached.

8. A method as set forth in claim 7 and including the step of extendingsaid eutectic bond into said opening.

9. A method as set forth in claim 7 and including the step of formingsaid silver member from pure silver.

10. A method as set forth in claim 7 and including the step of snuglyfitting said second portion of said silver member into said opening.

11. A method as set forth in claim 7 and including the step ofoverlapping said external side of said one wall of said switch armcompletely around said opening with said first portion of said silvermember.

12. A method as set forth in claim 7 wherein said are is performed by atungsten heliarc.

References Cited UNITED STATES PATENTS 3,015,022 12/1961 Bowers 2191273,180,022 4/1965 Briggs et al. 29504 XR 3,299,240 1/ 1967 Foti 200-48 XR3,310,388 3/1967 Bennett et al. 29504 XR 1,346,054 7/ 1920 Pennington219-1505 3,243,561 3/1966 Foti 200-48 XR 1,296,651 3/ 1919 Gravell219l50'.5 XR

FOREIGN PATENTS 12,984 10/ 1885 Great Britain.

JOSEPH V. TRUHE, Primary Examiner M. C. FLIESLER, Assistant Examiner US.01. X.R. 219-117, 127

